Multiple save :(

Goodday, please check my script first. I'll explain later.

PHP Code:

function detailsave($idshipping = NULL)
        {
            $table = 'sidetail';
            $data = array();            
            foreach($_POST['gname'] as $symb => $key)
                {
                    $data = array('idshipping' => $idshipping,
                                  'goodname' => $_POST['gname'][$symb],
                                  'nettweight' => $_POST['gnweight'][$symb],
                                  'grossweight' => $_POST['ggweight'][$symb],
                                  'qty' => $_POST['gqty'][$symb]
                                  );
                }
                    $this->db->insert_batch($table,$data);
    } 


I've been surfing in internet to search about how to fix error in my script. And i found tutorial about insert_batch. Well, i try with that method but still fail.  bunch of warnings appeared when i try the code above